Answer the questions. 1. What is called an ecosystem?

1. What is called an ecosystem?

2. What maintains an overall balance in the system?

3. What alters the environment?

4. When was the balance of nature first disturbed?

5. What influences greatly the environment in recent years?

2. Translate the following sentences:

1. For many centuries the problem of air pollution was not paid attention to. 2. We ought to protect the environment for it is in danger of human activity. 3. Industrial enterprises must use filters for exhaust gases to be purified. 4. They investigated carbon monoxide and sulphur oxide for the reason of their toxic properties. 5. The experiment lasted for three hours. 6. The ecosystem has a definite role to play for an overall balance has to be maintained. 7. Plants and animals fail to live without oxygen. 8. Many countries on the globe fail to fight man-made pollution. 9. The experiment was very tedious but they failed to get the desirable results. Transportation devices all over the world fail to prevent air from exhaust gases pollution. 10. Their attempt to make this experiment failed.

3. Translate the sentences:

1. The problem concerned is known to be the most difficult one. 2. Having investigated the properties of this polymer they come to a definite conclusion. 3. The experiment being very important, we paid special attention to the product obtained. 4. The problem of environmental protection is very important, a special committee having been set up under the UNO. 5. The development of modern industry is likely to be accompanied by the development of wasteless production. 6. Concentration of CO happens to be rather high in air. 7. Primitive man appeared to disturb the balance of nature by farming and cattle breeding. 8. Ultraviolet radiation from the Sun seems to make the evaporation of some substances from trees and Earth's crust to react with atmospheric oxygen.